Carbon Budget for a Large Drowned River Valley Estuary Adjacent to an Emerging Megacity (Sydney Harbour)

Abstract

Annual organic and inorganic carbon budgets were constructed for the Sydney Harbour Estuary. Net ecosystem metabolism was the main control on carbon fluxes in the system. Sydney Harbour Estuary was slightly net heterotrophic, which is consistent with a small CO 2 emission of 0.8 × 10 8 mol C yr −1 . Terrestrial carbon loads were 70% dissolved inorganic carbon, 21% dissolved organic carbon, and 9% particulate organic carbon. Dissolved inorganic carbon was exported to the ocean (4.19 × 10 8 mol C yr −1 ), and an import of organic carbon (1.92 × 10 8 mol C yr −1 ) from the ocean was required to balance the budget. Sydney Harbour had high sediment organic carbon burial rates similar to other river valley estuaries including the Hudson River and Chesapeake Bay. Productivity was the main sink of inorganic carbon followed by sediment burial, emissions of CO 2 to the atmosphere, and oyster sequestration. This study highlights the importance of determining the sources, sinks, and transformations of all carbon forms in constructing estuarine budgets.

Reduction in Riverine Freshwater Supply Changes Inorganic and Organic Carbon Dynamics and Air‐Water CO2 Fluxes in a Tropical Mangrove Dominated Estuary

“…Besides the trophic state, physical forcing can also govern the air‐water CO 2 fluxes from estuaries (Van Dam, Crosswell, Anderson, & Paerl, 2018). Recent estimates suggest that global estuaries emit CO 2 at a rate of about 0.25 PgC yr −1 (Ward et al., 2017; Tanner and Eyre, 2020, and references therein). Friedlingstein et al.…”

Distribution and Dynamics of Dissolved Organic Matter in the Changjiang Estuary and Adjacent Sea

“…Assuming that removal efficiency is the same in spring and autumn, it is estimated that 2.2 ± 1.6 × 10 11 moles of DOC were removed in the CEAS throughout the year. This rate of removal is comparable with annual terrigenous DOC mineralization (∼0.8 × 10 11 moles) in the Mississippi-Atchafalaya River influenced Louisiana Shelf (Fichot & Benner, 2014), but it is obviously higher than the total organic carbon loss of the Hudson Estuary (∼3.0 × 10 9 moles) in the United States (Tanner & Eyre, 2020) and Sydney Harbour Estuary (∼0.4 × 10 9 moles) in Australia (Cole & Caraco, 2005). Although degradation mechanisms may be antagonistic, the net effect of multiple mechanisms will be to turn the estuary into a DOM "filter.…”

A Modeling Approach for Addressing Sensitivity and Uncertainty of Estuarine Greenhouse Gas (CO2 and CH4) Dynamics

“…The initial concentrations of DIC and CH 4 in the riverine inflows and WWTP discharges were first constrained based on the literature values and then integrated into the PEST for optimization and uncertainty analysis. Riverine DIC concentrations and inflow rates commonly follow power law trends (Rosentreter & Eyre, 2020; Tanner & Eyre, 2020). This trend was applied in this study with average DIC concentration measured during the two field campaigns and riverine inflow rates in the Brisbane River Estuary.…”